Eukaryotic Cellular Components and Cell Theory

Intermediate filament

A type of cytoskeletal fiber that anchors the nucleus and organelles.

Ribosomes

Cellular structures that synthesize proteins via translation, found free-floating or attached to the endoplasmic reticulum.

Rough endoplasmic reticulum (RER)

Part of the endomembrane system, studded with ribosomes, involved in modifying and transporting proteins that will be inserted into membranes, exported, or sent to other organelles; also creates phospholipids.

Nucleus

The information center found only in Eukaryotes, where DNA is contained, protected, and regulated for transport in and out through small pores.

Nucleolus

A prominent structure within the nucleus that is the site where the components of ribosomes are made.

Chromatin

Fibers made of DNA and organizational proteins called histones, which condense into chromosomes during cell replication.

Golgi apparatus

A cellular organelle that further modifies proteins, synthesizes some polysaccharides, and serves as a packaging and final shipping center for vesicles.

Golgi vesicle

Membrane-bound sacs that bud off the Golgi apparatus, transporting substances to specific destinations.

Cytoplasm

The entire contents within the plasma membrane of a cell, consisting of the cytosol and all organelles.

Vacuole

Large membrane-bound sacs that bud off from the ER or Golgi apparatus, involved in storage, waste removal, or expelling excess water.

Mitochondria

Double membrane-bound organelles where cellular respiration occurs, converting food molecules into ATP, the cell's energy currency.

Plasma Membrane

The outer boundary of the cell's cytoplasm, regulating what enters and exits the cell.

Microtubule

The tiniest tubes of the cytoskeleton, involved in the movement of cilia, flagella, chromosomes, and organelles.

Centrosome

An organelle made up of a pair of centrioles, responsible for managing chromosome movement during mitosis.

Microfilament

Tiny filaments of the cytoskeleton, involved in changes in cell shape and the formation of a cleavage furrow during cell division.

Lysosome

A membrane-enclosed sac of digestive enzymes found in animal cells, capable of breaking down large molecules, destroying harmful bacteria, recycling worn-out organelles, and sculpting tissues.

Smooth endoplasmic reticulum (SER)

Part of the endomembrane system that lacks ribosomes and is involved in lipid synthesis, carbohydrate metabolism, calcium ion storage, and detoxification.

Secretory vesicle

Vesicles containing substances destined for export out of the cell, which are delivered to the cell membrane.

Cell Theory

A fundamental biological principle stating that all living things are made of cells, all cells come from other cells, and cells are the basic unit of life.

Prokaryote

A type of cell that does not have a membrane-bound nucleus or other membrane-bound organelles.

Eukaryote

A type of cell that possesses a true membrane-bound nucleus and other membrane-bound organelles.

Nuclear pores

Small openings in the nuclear envelope that allow the transport of items in and out of the nucleus.

Deoxyribonucleic Acid (DNA)

A very large molecule, made of repeating smaller building blocks called nucleic acids, that stores long-term genetic information in all living things.

Nucleotide

The building monomer of large nucleic acid structures, composed of a 5-carbon (deoxy)ribose sugar, a phosphate group, and a nitrogenous base.

Nitrogenous bases (DNA)

Adenine, Guanine, Cytosine, and Thymine; the components of DNA that carry genetic information.